Whipstock retrieving overshot

ABSTRACT

The present invention discloses a whipstock retrieval assembly for use in a wellbore to retrieve a downhole tool such as a whipstock from a borehole. In one aspect, the retriever includes a threaded barrel which is received over the tray end of the whipstock, and a securing member, preferably a conical member, pinches the whipstock tray portion received in the retriever against the barrel to prevent loss of the whipstock from the retriever as it is pulled from the borehole. In a second aspect, the retriever assembly includes a hook which is placed in a pre-supplied slot in the whipstock, and a shroud is deployed over the extending end of the whipstock to provide a smooth surface to pull the retriever and whipstock from the borehole.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The invention is related to a downhole milling and drilling assembly, more particularly to a downhole tool retrieval assembly, and more particularly to a whipstock retrieval assembly having a mechanism to enhance the likelihood of successfully retrieving the whipstock from a downhole location.

[0003] 2. Background of the Related Art

[0004] In the drilling of oil and gas wells, lateral wellbores are often required to form another wellbore into an adjacent formation, to provide a perforated production zone at a desired level, to provide cement bonding between a smaller diameter casing and the adjacent formation, or to remove a loose joint of surface pipe. To create the lateral wellbore, milling tools are used for removing a section or a “window” of existing casing from a primary wellbore. The milling tools have cutting blades and typically utilize a diverter such as a whipstock to cause the tool to be moved laterally while it is being moved downwardly and rotating in the wellbore to cut an angled opening, pocket, or window in the well casing or the borehole.

[0005] Formation of a lateral wellbore is typically performed in a step saving manner according to the following steps: An anchoring member or packer is set in a wellbore at a desired location below the location where the lateral wellbore will be formed. The packer acts as an anchor against which tools above it may be fixed in place in the wellbore. The packer typically has a key or other orientation indicating member, and the packer's orientation is checked by running a tool such as a gyroscope indicator into the wellbore. A whipstock/cutter combination tool is then run into the wellbore and landed in the packer whereby the whipstock is oriented in the direction of the desired lateral wellbore. The cutter is connected to the whipstock by a shearable member, like a bolt. In this manner, the cutter and whipstock can be run-in to the well together, saving an additional trip. Pushing on the cutter shears the bolt, freeing the cutter from the tool. Rotation of the string and the cutter can then begin the formation of the lateral wellbore.

[0006] After the whipstock has served its purpose, it typically must be removed from the borehole. In some cases, the whipstock will include a slot therein, into which a hook suspended on the end of a drill string or the like is inserted. The slot is typically provided through the wedge portion of the whipstock, adjacent to, but spaced from, the upper terminal end of the whipstock. The hook is then retracted up the bore, pulling the whipstock upwardly therewith. However, it is known for the whipstock to tilt about the hook location as it is being retracted up the bore such that the portion of the whipstock above the hook can move radially outward and become hung up on downhole equipment such as gas lift mandrels and the like. Additionally, the whipstock may become otherwise pinched or stuck in the hole. As a result, the hook can become disengaged from the slot, or, on occasion, the hook may deform and pull through the slot. Some whipstocks do not come equipped with a hole for hook-based retrieval, and must be retrieved by an alternate methodology. In this whipstock configuration, an overshot tool having an open cylindrical treaded interior is landed upon the upper end of the whipstock and is rotated thereon until it is threaded over this upper end to grip the whipstock therein. The whipstock, once received therein, is pulled from the hole. However, as previously discussed, the whipstock can become stuck in the hole and disengaged from the retriever.

[0007] There is a need therefore for a whipstock retrieving apparatus and method having a greater likelihood of successfully and easily retrieving the whipstock from the bore.

SUMMARY OF THE INVENTION

[0008] The present invention provides methods and apparatus for securely removing a whipstock, or other article placed or lost in a wellbore, such that the likelihood of successful retrieval is enhanced.

[0009] In one embodiment, the invention includes a retrieval member, which includes a hook for engagement with a slot in the whipstock, and a securing element, preferably a sleeve, which, when the hook is engaged in the slot, receives the end of the whipstock up-bore from the slot therein. Thus, as the whipstock is retrieved upwardly on the hook, the upper extending portion thereof is covered by the sleeve and cannot rock out to become tangled with an impediment to retrieval located in the borehole. Once the whipstock is retrieved, the hook is disengaged from the whipstock to free the whipstock from the retriever.

[0010] In another embodiment, the whipstock retriever apparatus includes an open cylindrical internally threaded member, which is landed upon the whipstock and rotated thereover to receive the tray end of the whipstock within the cylindrical member. The retriever apparatus further includes an internal conical member which is preferably disposed with and co-linearly extensible with the centerline of the cylindrical member, and is biasable to an extended position therein. As the retriever apparatus threads itself onto the tray portion of the whipstock, the internal canted surface of the whipstock is wedged between the conical outer wall of the cone and the internal threaded surface of the cylindrical member to securely grip the whipstock within the retriever. The retriever can then be pulled from the bore with the whipstock securely wedged therein. Upon removal of the tool from the well, the cone is retracted from the gripping position to allow removal of the whipstock from the retriever.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of this invention and are therefore not to be considered limiting of its scope, for the invention may admit to other equally effective embodiments.

[0012]FIG. 1 is a view of a whipstock disposed in a borehole, showing the basic features thereof;

[0013]FIG. 2 is a partial view of the whipstock of FIG. 1 rotated ninety degrees, showing the configuration of a retrieving slot therein;

[0014]FIG. 3 is a sectional view of a first embodiment of the retriever of the present invention, showing the retriever positioned adjacent to a whipstock for retrieval thereof from the borehole;

[0015]FIG. 4 is a sectional view of the retriever of FIG. 3, showing the retriever of the first embodiment engaging the whipstock in the borehole;

[0016]FIG. 5 is a sectional view of the first embodiment of the retriever as shown in FIG. 3, showing the retriever received on the whipstock and positioned to pull the whipstock from the borehole;

[0017]FIG. 6 is an exploded view of a second embodiment of a retriever of the present invention;

[0018]FIG. 7 is a sectional view of the second embodiment of the retriever as shown in FIG. 6, showing the retriever prior to the engagement thereof with a whipstock in a borehole;

[0019]FIG. 8 is a sectional view of the second embodiment of the retriever as shown in FIG. 6, showing the receiver engaging the whipstock in the borehole;

[0020]FIG. 9 is a sectional view of the second embodiment of the retriever as shown in FIG. 6, showing the retriever fully engaged on the whipstock in the borehole;

[0021]FIG. 10 is a partial sectional view of the second embodiment of the retriever as shown in FIG. 6; and

[0022]FIG. 11 is a front view of a shroud of the second embodiment of the retriever as shown in FIG. 6.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0023]FIG. 1 is a schematic view of a whipstock 100, installed in a wellbore 101 and retrievable using the methods and apparatus of the present invention. For purposes of illustration, the whipstock 100 preferably includes, at its upper end (defined as the end thereof nearest the ultimate opening of the wellbore at the earth's surface), a tray 104 that forms a wedge shape in order to cooperate with a milling tool (not shown) to facilitate the formation of a window (not shown) in the wellbore 101, i.e., the wedge pushes the milling tool into the side of the wellbore and thus redirects the wellbore in an offset direction approximately equal to the offset between the wellbore centerline and a plane of the tray 104. The tray 104 preferably has a terminal end 105 located at the furthest most upward extension of the whipstock 100 in the wellbore 101, a semi-circumferential outer surface 106 formed as a portion of a cylinder, and an inner wall portion 108 formed as the planar slanted portion of the tray 104 used to guide the milling tool to create the window.

[0024] Two types of whipstocks can be used. In one case, the tray 104 includes a slot 110 (shown in FIG. 2) extending therethrough and opening through both the outer surface 106 and the inner wall portion 108. As shown in FIG. 2, the slot 110 includes a first, generally semicircular, wall portion 112 located at the furthest most position of the slot 110 from the terminal end 105, a second generally semicircular wall portion 114 located at the end of the slot 110 located closest to the terminal end 105, and opposed walls 116, 118 extending therebetween and slanted inwardly of the slot in the direction of the terminal end 105. In a second style of whipstock in use, no slot is provided for retrieval.

[0025]FIG. 3 through FIG. 5 illustrate a first embodiment of a whipstock retriever 300 of the present invention. In this embodiment, the retriever 300 includes a barrel 120 that is generally a cylindrical tubular shape that can be positioned over the tray 104 of the whipstock 100 and a pinch member 122 that is selectively positionable to engage the inner wall portion 108 of the tray 104. The pinch member 122 pinches that portion of the tray 104 that receives the retriever 300 between the pinch member 122 and a threaded bore 128 of the barrel 120.

[0026] Referring to FIG. 3, the retriever 300 is shown positioned adjacent to and slightly spaced from the terminal end 105 with the pinch member 122 fully extended within the barrel 120. The barrel 120 includes an open end 126 and the threaded bore 128 with threads extending inwardly of the open end 126. Opposed to the open end 126 of the barrel 120 is a back cover plate 130 that includes an attachment mechanism for connecting to a drill string 132. Within the cylindrical envelope formed by the barrel 120 and the cover plate 130 is provided the pinch member 122 that is preferably conical in shape. The pinch member 122 can have a retraction assembly 136 that is attached at one end thereof to the cover plate 130 and has a pneumatic piston bore 138 formed by the inside of a cup 150 threaded at its open end over the pinch member 122. To form the remainder of the piston bore 138, the cup 150 includes an annular base 152 having a piston aperture 154 formed generally concentrically in the center thereof and a seal 155 disposed in the piston aperture 154. The retraction assembly 136 is actuable about the cup 150 and includes a rod 160 extending from within the cup 150 through the piston aperture 154 in the annular base 152 and thence into threaded engagement with a bore 131 in the cover plate 130. The rod 160 has a piston 162 received at the end thereof disposed within the cup 150. The piston 162 is preferably a low aspect ratio cylinder having a circular shape about its outer circumference and a seal 166 disposed therein. Thus, a piston chamber 168 is formed within the piston bore 138 that is bounded by the piston 162, the annular base 152, the rod 160 extending from the piston 162 to the annular base 152, and the inner cylindrical surface of the cup 150. An aperture 161 in the rod 160 allows fluid communication with the piston chamber 168 since fluid can flow through the drill string 132 and a bore 133 that extends through the back cover plate 130, the rod 160, and the pinch member 122. A retainer ring 156 disposed within the piston chamber 168 prevents the piston 162 from contacting the annular base 152 of the cup 150 thereby ensuring that the aperture 161 in the rod 160 remains open to fluid communication. Since the end of the rod 160 extending outwardly from the piston bore 138 is grounded against movement by threaded engagement in the bore 131 in the cover plate 130, pressurization of piston chamber 168 causes the cup 150, and thus pinch member 122 threadingly attached thereto, to move along the piston bore 138 in the direction of the cover plate 130, i.e., to retract inwardly of the barrel 120. This can be accomplished by increasing the fluid flow through the drill string 132 since a choke 158 positioned in the rod 160 past the aperture 161 causes a differential in pressure that increases the pressure of the fluid in the piston chamber 168.

[0027] To extend the pinch member 122 away from the cover plate 130, a biasing member such as a spring 170 is located about the rod 1160 and is grounded at one end thereof in pressing contact with the back cover plate 130 and at its other end in pressing contact with the annular base 152. The spring 170 is sized and chosen to provide a constant urging action of the pinch member 122 in the direction of the open end 126 of the barrel 120.

[0028] The pinch member 122 is preferably an elongated conical member having a conical surface 176, such that the minor diameter 178 of the pinch member 122 is located adjacent the open end 126 of the barrel 120. The conical surface 176 is splayed at an angle chosen to be approximately equal to the slant angle of the tray 104 of the whipstock 100. Therefore, the conical surface 176 of the pinch member 122 is substantially parallel to the inner wall portion 108 of the tray 104 when the threaded bore 128 is positioned over the outer surface 106 of the tray 104.

[0029]FIG. 3 through FIG. 5 show the sequence of operation of engaging the retriever 300 of the present invention over the whipstock 100. Starting at FIG. 3, the retriever 300 is positioned adjacent to and slightly spaced from the tray 104. The retriever 300 may be rotating; however, the whipstock 100 is stationary in the wellbore 101. The drill string 132 is lowered in order to land the retriever 300 at the tray 104, and the retriever is rotated and if necessary moved axially in the wellbore 101 in order to obtain entrance of the tray 104 into the open end 126 of the barrel 120 as shown in FIG. 4.

[0030]FIG. 4 illustrates the retriever 300 moved onto the tray 104 of the whipstock 100 where the conical surface 176 can be seen to be in a generally spaced and parallel position with respect to the inner wall portion 108 of the tray 104. In this position, the retriever 300 begins to grip the whipstock 100 for secure retrieval. As the barrel 120 of the retriever 300 continues to both rotate and move axially over the outer surface 106 of the tray 104 of the whipstock 100, the conical surface 176 engages against and slides over the inner wall portion 108 in a rotational motion. As this occurs, the conical surface 176 of the pinch member 122 urges the outer surface 106 of the tray 104 received within the barrel 120 against the threaded bore 128 of the barrel 120 since the pinch member 122, and thus the conical surface 176, are biased by the spring 170 outwardly of the back cover plate 130 of the barrel 120. Thus, threads on the threaded bore 128 engage and can dig into the outer surface 106 of the tray 104, and the conical surface 176 continues to push the tray 104 against the threaded bore 128. The tray 104 is fully received in the retriever 300 when the terminal end 105 of the tray 104 is received adjacent the inward most threads of the threaded bore 128 as shown in FIG. 5. This can be detected by a change in torque resistance in the drill string 132, a change in power input to the drill string, or by a predetermined extension of the drill string 132 into the wellbore 101 after landing the retriever 300 upon the whipstock 100.

[0031] The whipstock 100 may be retrieved from the wellbore 101 once the retriever 300 is positioned as shown in FIG. 5. To retrieve the whipstock 100, the drill string is pulled from the wellbore, and then the whipstock with the tray 104 securely pinched between the conical surface 176 of the pinch member 122 and the threaded bore 128 of the barrel 120 is pulled through the wellbore to the surface. If the whipstock 100 becomes stuck in the wellbore 101 while being pulled therethrough, the retriever 300 can be released from the whipstock by operating the retraction assembly 136 and retracting the pinch member 122 as described above. Once the whipstock 100 is retrieved from the wellbore, it is removed from the retriever 300 by providing compressed fluid into the piston chamber 168 in order to urge the pinch member 122 inwardly in the barrel 120 and thus against the bias of the spring 170. This removes the pinch member 122 from engagement with the tray 104, and allows the whipstock 100 to be removed from the barrel 120 of the retriever 300.

[0032] Referring now to FIG. 6 through FIG. 9, there is shown an additional embodiment of a retriever 300 that has particular utility where a hole, such as the slot 110 (see FIG. 2), is provided extending through the tray 104. In this embodiment, a hook 200 is provided as in the prior art, and an additional securing mechanism 202 is provided to secure the hook 200 in the slot 110 in order to prevent unintended withdrawal thereof from the slot 110 as the whipstock 100 is retrieved by the retriever 300 from the wellbore 101.

[0033] Referring first to FIG. 6, the retriever 300 is shown in an exploded view. The retriever 300 generally includes an extending rod like hook base 206 which is securable on the end of a drill string (not shown), and having a hook 200 disposed at the free end thereof and a securing mechanism 202 formed in part by a rotationally positionable shroud 204 located intermediate either end of the hook base 206 and being actuable therefrom as will be further described herein. When in a retrieving position to pull the whipstock 100 from the wellbore 101 as shown in FIG. 9, the hook 200 is received through the slot 110 in the tray 104 of the whipstock 100, and the terminal end 105 of the whipstock 100 is received between the shroud 204 and the hook base 206. Thus, as the whipstock 100 is pulled up the wellbore 101, the shroud 204 covers the extending portion of the tray 104 preventing interference of it with hangers, etc. positioned in the wellbore 101.

[0034] To accomplish proper positioning of the shroud 204 for connection of the retriever 300 to the whipstock 100 and during retrieval, the shroud 204 is pivotally connected to the hook base 206 about a pivot pin 224 and is positioned about the axis formed at the pivot pin 224 by the shroud positioner 210 extending between the shroud 204 and the hook base 206. As shown in FIG. 10 and FIG. 11, the shroud 204 comprises a generally semi-cylindrical section, having a generally semicircular inner portion 212 sized to be located over the generally cylindrical hook base 206 (shown in phantom in FIG. 10) and a generally cylindrical outer portion 231 configured to be received within the wellbore and opposed a pivot end 214 and a tray receiving end 216. In operation, the pivot end 214 pivotally connects to the hook base 206, and the shroud 204 extends therefrom in the direction of the hook 200. The shroud positioner 210 is located on the hook base 206 adjacent to and extending between the pivot end 214 and the hook base 206.

[0035] Referring now to FIG. 6 and FIG. 10, to pivotally attach the pivot end 214 of the shroud 204 to the hook base 206, the shroud includes a pair of holes 218, 220 (only one of which is shown in each of FIGS. 6 and 10) extending through the shroud wall adjacent to the pivot end 214 and collinearly disposed. Thus, the pair of holes 218, 220 are located in an opposed relationship on the shroud 204 by 180 degrees. The hook base 206 includes a through bore 222 over which the holes 218, 220 in the shroud 204 align such that the pivot pin 224 may pass therethrough and be maintained in place with cotter pins or the like (not shown). Thus, the shroud 204 may pivot about the hook base 206 at the location of the pin 224.

[0036] To position the shroud 204 with respect to the hook base 206, the shroud positioner 210 includes a lever 226 received at one end thereof in pivotable, yet locking, relationship with the hook base 206. The lever 226 extends from its location on the hook base 206 and terminates a distance in the direction of the tray receiving end 216 of the shroud 204. Preferably, the lever 226 is a generally planar metal strip having an offset or S-shaped profile secured at one end thereof to the hook base 206 by a fastener 211 such as a bolt, a rivet, or the like that is secured in a mating aperture in the hook base 206. Therefore, the lever 226 extends radially outward from the hook base 206 at a distal end portion 213 thereof. By configuring the positioner 210 with the lever 226 in the S-shape, it has an inherent leaf spring effect at each of the curves of the S-shape in order to cause the distal end portion 213 to naturally space itself from the hook base 206. A pin 205 extends from the hook base facing side of the distal end portion 213 of the lever 226 and is receivable in a bore 232 extending inwardly of the hook base 206. A biasing member, such as a coil spring 230 surrounding the pin 205, is received in the bore 232 in the face of the hook base 206 and is engageable with the lever 226 proximate its distal end portion 213. The positioner with the spring 230 is operable to allow the shroud 204 and the hook base 206 to move in a lever motion about the pin 224 at the pivot end 214 of the shroud 204. To further ensure spacing between the inner portion 212 of the shroud 204 and the hook base 206, a pair of pins 234, 239 can be received in mating bores (not shown) in the hook base 206 to extend outwardly and engage the inner portion 212 of the shroud 204 when the shroud is pushed against the hook base 206, such as when the retriever 300 is being lowered into the wellbore.

[0037] Referring still to FIG. 6, the retriever 300 includes a drill string attachment end 236 extending from an end of the hook base 206 opposite the hook 200. A shank portion 242 of the hook 200 extends generally perpendicular to the longitudinal axis of the hook base 206 and opposed to the generally concave portion of the shroud 204. The shank portion 242 has a similar truncated triangular cross section as the slot 110 (shown in FIG. 2). The hook 200 further includes at its terminal end as extended from the hook base 206 a flange 260 adjacent to the shank portion 242 extending outwardly thereof about its perimeter.

[0038] As shown in FIG. 7, the retriever 300 is positioned in the wellbore 101 adjacent to and spaced from the terminal end 105 of the tray 104 of the whipstock 100. In this position, the hook 200 is positioned adjacent to, yet not yet over, the terminal end 105 of the tray 104. Referring now to FIG. 8, the retriever 300 is shown positioned with the hook 200 advanced along the tray 104 of the whipstock 100 just prior to positioning of the hook 200 in the slot 110. In this position, the terminal end 105 of the tray 104 is positioned adjacent to the tray receiving end 216 of the shroud 204. The movement of the receiver 300 toward the whipstock 100 causes the hook 200 to ride up on the inner wall portion 108 of the tray 104 of the whipstock, thereby pushing the retriever 300 to one side of the wellbore 101 and allowing the tray receiving end 216 of the shroud 204 to move away from the hook base 206 creating a larger gap between the shroud 204 and the hook base 206 into which the tray 104 of the whipstock 100 is received as shown in FIG. 9.

[0039] As shown in FIG. 9, the whipstock 100 is fully received in the retriever 300 with the hook 200 having engaged through the slot 110 such that the flange 260 extends against the outer surface 106 of the tray 104 and the receiver 300 having received the tray 104 between the shroud 204 and the hook base 206. To provide the proper position of the hook 200 in the slot 110, the retriever 300 can be moved laterally downward in the wellbore 101 until the hook 200 engages the slot 110. As the hook 200 pushes into the wellbore 101, the hook engages the tray 104 causing the hook base 206 to tilt slightly since the tray 104 is tapered. Thus, the tilt is compensated and the hook 200 naturally pushes into the slot 110 when the hook 200 reaches the slot 110. The beginning of retrieval of the whipstock pulls the hook 200 upwardly in the slot 110 thereby placing the flange 260 in position against the outer surface 106 of the tray 104 and locking the hook 200 in place for retrieval.

[0040] As the retriever 300 is pulled from the wellbore 101, the shroud 204 protects the tray 104 from contact with downhole obstructions in order to increase the likelihood of successful retrieval. Once the whipstock 100 is pulled from the wellbore 101, it can be readily unhooked from the retriever 300.

[0041] While foregoing is directed to the preferred embodiment of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow. 

1. A downhole tool retrieving assembly for use in retrieving downhole tools from a bore comprising: a tool engagement member positionable into the bore and retrievable therefrom; and a tool security member disposed to engage with the downhole tool to ensure retention thereof with said tool engagement member.
 2. The downhole tool retrieving assembly of claim 1, wherein the security member is selectively disengageable from the downhole tool.
 3. The downhole tool retrieving assembly of claim 1, wherein the security member is selectively disengageable from the downhole tool by providing a fluid to the downhole tool.
 4. The downhole tool retrieving assembly of claim 1, wherein the security member is selectively disengageable from the downhole tool by providing a hydraulic fluid to the downhole tool.
 5. The downhole tool retrieving assembly of claim 1, wherein: said engagement member includes a hook; and the downhole tool includes a receiving member for receipt of said hook therein.
 6. The downhole tool retrieving assembly of claim 5, wherein the receiving member is a slot extending inwardly of the downhole tool.
 7. The downhole tool retrieving assembly of claim 5, wherein said security member further includes a shroud positionable in conjunction with said hook to receive at least a portion of the downhole tool therein.
 8. The downhole tool retrieving assembly of claim 7, wherein: the downhole tool is a whipstock having a tray; and a portion of said tray is received in said shroud upon engagement of said hook with the slot.
 9. The downhole tool retrieving assembly of claim 8, further comprising a shroud positioning apparatus to position said shroud relative to said hook as the retrieval assembly is received on the whipstock.
 10. The downhole tool retrieving apparatus of claim 9, wherein said positioning assembly includes: a hook base having said hook extending therefrom; a biasing member connected at one end thereof to said hook base and positioned intermediate said hook base and said shroud; said shroud hingedly connected to, and arcuately actuable about, said hook base; and said biasing member positioned to assist said shroud to arcuately actuate about said hook base.
 11. The downhole tool retriever assembly of claim 10, wherein the biasing member is a lever.
 12. The downhole tool retriever assembly of claim 1, wherein said tool engagement member includes a cup receivable over the downhole tool and engageable therewith.
 13. The downhole tool retriever assembly of claim 12, wherein said tool security member includes a pinch member to engage the downhole tool when the downhole tool is engaged by said cup.
 14. The downhole tool retriever assembly of claim 13, wherein the cup has profiles on an inside surface thereof for engaging the downhole tool.
 15. The downhole tool retriever assembly of claim 13, wherein the cup has threads on an inside surface thereof for engaging the downhole tool.
 16. The downhole tool retriever assembly of claim 13, wherein said cup is generally cylindrical with a longitudinal axis and said pinch member includes a conical element positioned substantially collinear with an axis of said cup.
 17. The downhole tool retrieval assembly of claim 16, further comprising a biasing member to relatively bias said conical member and cup to pinch the downhole tool therebetween.
 18. The downhole tool retrieval assembly of claim 17, wherein said biasing member is disposed and engaged between said cup and said conical member.
 19. The downhole tool retrieval assembly of claim 18, wherein the downhole tool is a whipstock.
 20. A method of retrieving a downhole tool from a borehole, comprising: providing a tool engagement member in position adjacent to the tool; providing a tool security member; engaging the tool with the engagment member; and securing the tool, at least with respect to the engagement member, with the securing member.
 21. The method of claim 20, further comprising retrieving the tool from the borehole.
 22. The method of claim 20, wherein: the engagement member includes a hook; and the downhole tool includes a receiving member for receipt of said hook therein.
 23. The method of claim 22, wherein the receiving member is a slot in the downhole tool.
 24. The method of claim 22, wherein the security member includes a shroud arcuately positionable with respect to the hook.
 25. The method of claim 24, further comprising: positioning the hook adjacent the receiving member in the downhole tool; positioning a portion of the downhole tool adjacent to the shroud; and extending the hook into the receiving member and positioning the portion of the downhole tool into a protected position with the shroud.
 26. The method of claim 20, wherein the engagement member includes a cup.
 27. The method of claim 26, wherein the security member includes a pinch element.
 28. The method of claim 27, further comprising: engaging the downhole tool with the cup; and pinching the downhole tool between the cup and the pinch element.
 29. The method of claim 28, wherein engaging the downhole tool with the cup engages profiles on an inside surface thereof with the downhole tool.
 30. The method of claim 28, wherein engaging the downhole tool with the cup engages threads on an inside surface thereof with the downhole tool.
 31. The method of claim 28, further comprising: retrieving the downhole tool from the borehole; and disengaging the downhole tool from the engagement member. 